Placing a component at center both vertically and horizontally

[Sandeep Ghosh]

Hi Friends,
This code displays a textfield and button at the top of the frame .How could I put these two component just at the center of frame both horizontally and vertically.
Thanks in adv.
Sonu

public class mainapplic extends JFrame {
  public mainapplic() {
           TestPanel tp=new TestPanel();
          Container c=getContentPane();
          c.add(tp);
          setSize(400,400);
          setVisible(true);
          addWindowListener(new WindowAdapter(){
          public void windowClosing(WindowEvent evt)
          {
            System.exit(-1);
          }});
  }
  public static void main(String args[])
  {
    new mainapplic();
  }
}
class TestPanel extends JPanel {
  JTextField tf;
  JButton  jb;
  public TestPanel() {
  tf=new JTextField(20);
  jb=new JButton("Clear");
  add(tf);
  add(jb);
  }
}

[ June 13, 2002: Message edited by: Dirk Schreckmann ]

[alex earnshaw]

In your TestPanel constructor create a new panel, add your button/text field to that panel. Set the layout of the TestPanel to BorderLayout, then add the panel containing the button/text field to the CENTER of the TestPanel.

public TestPanel() {
  tf=new JTextField(20);
  jb=new JButton("Clear");
  JPanel panel = new JPanel();
  panel.add(tf);
  panel.add(jb);
  setLayout(new BorderLayout());
  add(panel);
  }

[ June 13, 2002: Message edited by: alex earnshaw ]

[Sandeep Ghosh]

Hi Alex,
Thanks for prompt reply,but problem still remain.2 Component is still shown at the top of the JFrame.
I am still waiting for the ans.
Thanks in adv
Sandeep

[Bosun Bello]

You have to get the screen size using the default toolkit first, then call setBounds passing as follows...
yourframe.setBounds(yourwindow.width/4, yourwindow.height/4, yourwindow.width/2, yourwindow.height/)
This is a crude way. I believe swing has some methods that may do it for you.

[Sandeep Ghosh]

Hi,
Thanks a lot for the soloution.I am also looking for some solution in swing and layout manager.Does anybody have any suggestion regardng this problem.

Sandeep

[Luis Araujo]

Check the Interface LayoutManager2. This should help.

[Sandeep Ghosh]

Hi Friend,
Problem with earlier suggestion that is using setBound(int,int,int,int) is that it is ignoring this method and using BorderLayout.Do I have to change the Layout.About using LayoutManager2 could you be more specific.
Thanks in adv
Sonu

[Sandeep Ghosh]

Hi Friend,
I am trying this one,but frmSize.width and frmSize.height is showing 0.0 and 0.0.Why?
Please anybody have any solution.
Thanks in adv.
Sonu
public mainapplic() {
TestPanel tp=new TestPanel();
Container c=getContentPane();
c.setLayout(xYLayout2);
Dimension dlgSize = tp.getPreferredSize();
Dimension frmSize = getPreferredSize();
Point loc = tp.getLocation();
System.out.println(frmSize.getWidth()+":"+frmSize.getHeight());
c.add(tp);
tp.setLocation((frmSize.width - dlgSize.width) / 2 + loc.x, (frmSize.height - dlgSize.height) / 2 + loc.y);
setSize(400,400);
setVisible(true);
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent evt)
{
System.exit(-1);
}});
}
[ June 15, 2002: Message edited by: Sonu Ghosh ]

[Shashi Kanta]

hi sonu,
u r trying to get the width and height in the constructor!!
get the width and height in some other method.
since the frame has not been yet created when u r calling the constructor, it'l give zero values.
by the way do u want to center ur text only or some components too? if text only, i can give u the code that'll work both in swings and awt.
rgds,
Shashi

[Shashi Kanta]

sorry, i can do with other components too.
if u r still having problem in putting the text and the buttons in the center of the table, i can help u.
rgds
shashi

[Sandeep Ghosh]

Hi Friend,
My Components(JTextField and JButton) are in JPanel.I want to put the JPanel in the center of the JFrame.Please help me,I am still waiting for the soloution.
Thanks in adv
Sonu

[Shashi Kanta]

hi sonu,
first of all, i have to tell u that the BorderLayout doesn't not respect the sizes of its components! so when u add a component to a container having BorderLayout, the component's size will be set according to the space available in the container. if u add 2 components, the available space will be divided equally among them and if u add one component only, the whole of the conatiner's size will be given to the component! thats what is exactly happening in your case. the JPanel gets all the space of the JFrame. and since in a JPanel, the components are laid out in a FlowLayout fashion, the components are displayed from top. so u see the JTextField and the JButton on top.
if u have only one component to add to a conatiner and want the component to be at the center, use either a GridBagLayout manager or don't use any layout, i.e. set the layout of the container to null and then place the component accordingly.
i have used null layout.
here's the code u want.

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class mainapplic extends JFrame {
public mainapplic() {
TestPanel tp=new TestPanel();
Container c=getContentPane();

setSize(400,400);

getContentPane().setLayout(null);

c.add("Center",tp);

setVisible(true);
//below, finding the hidden space and space from the edge of the JFrame to the JPanel
int hiddenHeight=getInsets().bottom+getInsets().top;
int hiddenWidth=getInsets().left+getInsets().right;
// now setting the location of the JPanel so that it's at the center of the visible area of the JFrame
tp.setLocation((getWidth()-hiddenWidth-tp.getWidth())/2,(getHeight()-hiddenHeight-tp.getHeight())/2);

addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent evt)
{
System.exit(-1);
}});
}
public static void main(String args[]){
new mainapplic();

}
}
class TestPanel extends JPanel {
JTextField tf;
JButton jb;
public TestPanel() {
tf=new JTextField(20);
jb=new JButton("Clear");
add(tf);
add(jb);
setSize(getPreferredSize()); // setting the size of the panel to just the required size for its components


}
}

///
hope thats what u want.
rgds
Shashi

[Sandeep Ghosh]

Hi Shashi ,
Sorry couldn't replied earlier.Thanks a lot for the help.
sonu